What’s the Difference Between Ironite & Milorganite?

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Written By: Mark Marino

a Massachusetts Core Applicator License holder and owner/operator of Lawn Phix,

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We all strive every year to get our lawns green – a deeper dark green lawn. With so many products and brands out there in the lawn care market, it can get confusing.

One question is around Ironite vs. Milorganite, and what’s the difference between these two products? That’s what we’re going to answer and clear up right now – simply.

What is the difference between Ironite vs. Milorganite?

Ironite is a 1-0-1 fast-release iron supplement for your lawn, while Milorganite is a 6-4-0 organic lawn fertilizer for your lawn. Ironite will help adjust iron deficiencies in your soil and provide a quick green-up to your grass, where Milorganite is a source of slow-release macronutrients like nitrogen and phosphorus.

Ironite vs. Milorganite

Nitrogen (N)1%6%
Phosphorus (P)0%4%
Potassium (K)1%0%
Iron (Fe)20%2.5%
Calcium (Ca)8%1.2%

The micronutrients and macronutrients outlined in the table above show the vast differences between Ironite vs. Milorganite. Ironite is used to help turn yellow or light green grass a darker green, and Milorganite can be used several times per year as part of your routine lawn care program.

Nitrogen fertilizer with an iron product such as Ironite is a surefire way to make your grass pop if your lawn is turning yellow.

Organic Lawn Fertilizer

Having healthy soil will result in a lush green lawn. Milorganite is an organic fertilizer that feeds both your soil and lawn. This lawn food contains nitrogen and phosphorus, while also providing some minerals such as iron and calcium. This granular fertilizer is non-burning and is a great organic option for a healthy lawn while improving your soil quality.

Unlike Ironite, Milorganite is a slow-release fertilizer with 6% Nitrogen (2.5% water-soluble nitrogen) 4% Phosphorus, and 2.5% Iron. will make your lawn lush and grass greener. Milorganite will help keep your lawn healthy while adding a deep green color.

Milorganite was previously packaged in 36-pound bags, but has since changed to a smaller 32-pound bag that covers 2,500 square feet. This bag rate supplies 0.77 pounds of Nitrogen per 1,000 square feet.

Milorganite has been in high demand and short supply in years past, and the cost has continued to steadily increase – so be prepared to find some Milorganite alternatives just in case.

Liquid & Granular Lawn Supplement

Ironite is a mineral supplement in the form of iron. Unlike Milorganite, Ironite does not deliver enough nitrogen or macronutrients and is not designed to use as part of your lawn feedings. If your soil test results come back with an iron deficiency, Ironite – a nutrient supplement – can improve the iron balance in your lawn.

Iron is needed in the plant to create chlorophyll, which is also necessary for photosynthesis in the grass. When combined with nitrogen and a balanced soil pH, you will see very quick results. Iron, in a chelated liquid form, is also commonly used when applying a lawn fungicide.

Ironoite comes in two forms: Granular Ironite and Liquid Ironite.

When it comes to iron supplements, we highly recommend both Iron Max (a chelated iron) or Turf Nectar AC over Ironite.

Can I use Ironite with Milorganite?

Depending on the results of your soil test, using both Milorganite and Ironite together may be too much iron at once. Too much iron can result in your grass turning black. Milorganite is slow-release and contains about 2.5% iron, where Ironite is a fast-release and contains 20% iron.

Which is better Ironite vs Milorganite?

This unfortunately is not an apples-to-apples comparison. Ironite is a nutrient supplement that can be used to treat iron chlorosis – or yellow grass blades – while adjusting any iron deficiencies in your soil. Milorganite is an organic lawn fertilizer that provides food in the form of macronutrients for your turf.

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Author's Note: this piece has been updated for accuracy since its first publication on
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Author: Mark Marino
My name is Mark Marino, and I am the founder, owner, and operator of Lawn Phix. With a passion for lawn care and turf nutrition for over a decade, I've dedicated countless hours to correcting soil and perfecting lawns. Today, my expertise, backed by formal courses at UMass Extension Pesticide Education, allows me to offer top-tier lawn care services and advice. I am a fully licensed and insured lawn care applicator in Massachusetts, specializing in comprehensive turf nutrition, weed control, and lawn pest control. My license number is AL-0053865. Contact me at [email protected] or +1 (508) 500-8402.

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